McCain Picks Sarah Palin..... ( Archived) (359)

Professor Barry Brook is Sir Hubert Wilkins Chair of Climate Change and Director of the Research Institute for Climate Change and Sustainability at the University of Adelaide.

"Claims that global warming stopped in [... insert convenient year] underscore a fundamental lack of understanding about the difference between a trend and variability - or else a deliberate attempt to mislead people with the intent of further delaying action on climate change.

The trend for global warming is consistently upwards, but in any given month, or even season or year, the actual temperature will be variable.

Let me illustrate by example. Based on the NASA GISS global meteorological station data, January 2008 was 'cool', at only +0.31°C above the 1950-1980 average. But March 2008 was back to +0.81°C. By comparison, January 1998 was +0.57°C and March 1998 was +0.70°C. In the northern hemisphere, March 2008 was the 2nd warmest month on record (relative to the average), with a +1.40°C anomaly (for reference, the hottest month on record was January 2007 at +1.61°C).

The point is, there is a lot of month-to-month variability, whatever month you happen to cherry pick. But the trend is consistently upwards - all of the above temperature anomalies are greater than the 1950-1980 average, by +0.3 to +1.6°C.

2008 is expected to be a slightly cooler year than 2007, largely because of a particularly intense La Niña and the current low solar activity.

Indeed, recent work has shown that the average temperature difference between the top and bottom of the 11-year solar cycle is almost 0.2°C (we are currently at the bottom). Looking forwards, recent predictions from the UK Hadley Centre are that at least half of the years between 2009 and 2014 will exceed the highest yearly global temperature to-date."



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